Thermostatic device



Den 2o, 1927.r 1,653,602

W. LINDEM'NN ET AL THERMOSTATIC DEVIGE Filed April` 24, 1925 IN VEN TORA ATTORNEY Aliatente'd 20',` 1927.

vUNITED STATES PATENT .oFFlcn WALTER C. LINDEHANN AND EDWIN' BUTEN BER,0F MILWAUKEE', WISCONSIN', AS- y SIGNORS T0 A. LINDEMANN & HOVERSONCOMPANY, 0F MILWAUKEE, WISCQN- SIN, 'A conronarIoN orv WISCONSIN.

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Application ld April 24, 1923. Seriallo. 634,246.

The improvements relate to devices for automatically controlling thetemperature of ovens and the like, and primarily ovens arranged to beelectrically heated. 'Iheir objects are, among others, the provision ofa thermostatic control which may be adjusted and set so as to maintainvarious temperatures by acting upon the heating medium and preventing itfrom raising the temperature above or permitting it to fall below thepredetermined point; to make the mech- Vanism whereby the control iseli'ected accurate and dependable in its operation, and to simplify andgenerally improve its construction.

The improvements are illustratedin the accompanying drawings, in whichFlgure 1 is a longitudinal vertical sectlonsubstantially on the line1-.1 of Fig. 2, looking in the direction of the pointers in that figure,and Fig. 2 is a transverse vertical section substantially on the line2-2of Fig. 1, looking in the direction indicated by the pointers inthatgure. v

In the said posed to the heated air of the oven interior.

The cap 3 is mounted. on 'the housing 4 by means of a key 5 engaging asuitable annular groove therein.= v Y `Fixed on the inside of the cap 3is a cam device consistingof disks having inturned annular flanges 6 and7, forming a channel eccentric to the axis on which the cap 3rotates, sothat the pin 8 which extends between the flanges will be moved radiallywhen the disk is rotated.

The pin 8 is carried by one arm 9 of a bell-crank pivoted at 10, and theother rarm 11 of this bell-crank has a pin 12 projecting in the oppositedirection, to that of the pm the cup memberl' a thermostatic band 17 issecured, one end of the band being fixed drawings 1 represents a por-ition of the door or wall of an oven or slm- -to the inner wall thereof,as shown Iat 17,

and the other to the shaft 16 through an arm 18 projecting from a collarkeyed there-v on. The shaft extends loosely through the centralhubportion 15a and has a dog 19 keyed thereon near its opposite end bymeans of a collar 19*l integral with said dog. By these means provisionis made for the adjustment of the position of the dog 19, and

,23 by a link 24, the former pivoted at 25 and connected with the latterby means of a short arm 26 extending from the pivot 25 and pivotallyconnected to thesaid link 24. vThe dog 19 has a shoe 29at its outer end,which engages the arm 20 and moves it counter-clockwise, as illustratedin Fig. 2, when the band 17 has expanded to. a-suicient extent to bringthe shoe in contact with the arm. e y Y i The switch employed comprisesvessels 27 and 28 of non-conductive material, pivoted on a spindle 30through a supporting frame-31 and each havinga drop of fluent conductivematerial -32 in its 'horizontal' bottom. y The electric terminals 33 and34 extend into the vessel and have enlarged .con

tactl points in proximity to each other at one end thereof, so that whenthe iuent conductory is in that endof the vessel it will be in contactwith both terminals and will close the circuit,' thus energizing theheating coils or the like. The pivoted frame 31 has a weighted extension31 on oneside of its pivot, which normally holds the vessel slightlycanted toward thatV side and the fluent conductor in circuit-closingposition. A stop pin limits 'the rocking'movement of thevessel-supporting framein both directions. When the`thermostatic bandhas been expanded by the heat in the oven to a sufficient extent to movethe dog 19 into contact with the arm 20, and the temperature continuesto rise, the arm 20 is moved and caused to rock the curved arm 23,through the link 24, and press its lower extremity 36 against the frame31 below its pivot, thus canting theL vessel slightly and causing itsbottom to incline away from the terminals,

and permit the fluent globule 32 to gravtate away from said terminals,thus breaking the circuit. If now the temperature falls below the givenpoint the dog 19 will be withdrawn from the arm 20 and the arm 23permitted to move to the left (Fig. 2) under the influence of theweighted extension 31, so that the vessel is canted in the oppositedirecttion and the fluid moved to circuit-closing position. To raise thetemperature of `the oven the dial cap 3 is rotated so as to withdrawnthe dog 19 from the arm 20, so that the circuit will remain closed untilthe temperature has risen to a point sufficiently high to bring the dogin contact with the arm` through the expansion of the band 17. If it isdesired to lower the temperature the cap is rotated in the oppositedirection thus causing the dog to press against the arm 2O and break thecircuit; and this condition will continue until the temperature hasfallen to a point suicient to cause a contraction of the thermostaticband which will withdraw the dog 19 from the arm 20.

The apparatus herein shown and described is primarily designed for usein connection with electrically heated ovens and the like, but may, withsmall modifications, be adapted for use in connection with other heatingmedia. Various changes in the construction and arrangement of the partsmay also be made without departing from the invention.

What we claim is:

1. In a device ofthe character described, a rotatable member, ahousingon which said member is mounted, a metallic member adapted to beexpanded by the action of heat, a connection between said rotatablemember and said metallic member compris-l ing a cam connectedv with saidrotatable member, an .arm engaging said cam and an operative connectionbetween the cani and the metallic member whereby movement of the formercauses a change in the position of the latter, a heat generating devicecontrol comprising means for making and breaking an electric circuit,and connecting means comprising a movable arm having a portion adjacentto said making and breaking means, a member connected With said metallicmember and movable therewith into and outof connection with the saidarm.

2. In a device of the character described, the combination of a vessel,fluent conductive material therein, electric terminals extending intosaid vessel and into the path of said fluent material, means formounting said vessel to be canted, and thereby to cause,y

the said fluent material to move to and from the electric terminals, andautomatic means for normally maintaining said vessel in a given positionand causing it to return to said position after being moved therefromcomprising a weighted portion associated with said last-named means, andthermostatically controlled and adjustable means for moving said vesselfrom such position, said fluent conductive material being in the form ofa globule and said vessel having a bottom in approximately horizontalposition, but arranged to assume positions slightly angular theretowhen-the vessel is canted and to cause the said conductive material toflow from one portion to another of said bottom.

3. In combination with an electric heat generating device and openterminals for a circuit for supplying electric energy thereto, of athermostatic opening and closing device therefor, comprising a movablemember, means for indicating the position of said member in terms oftemperature, a heat expansible device arranged to be exposed to the heatof the generator, a fluent metallic member adjacent to said terminalsand mounted to be moved into and out of contact therewith, automaticmeans for holding the same normally in contact therewith, connectingmembers between the last named member and the heatY expansible devicewhereby the expansion and contraction of the latter is communicated tothe former, andoperating connections between the movable member and thesaid connecting members whereby movement of the former varies theoperative relationship between said heat expansible member and thefluent metallic member adjacent to said terminals said operatingconnections comprising avessel along t-he bottom of which the saidfluent member moves into and out of contact with the said terminals. l

4. In the combination specied in claim 3, said automatic meanscomprising a. pivoted frame on which said fluent metallic member ismounted above its pivot, the center of gravity of said frame being atone side of said pivot.

5. In the combination specified in claim 3 said automatic meanscomprising a pivoted frame and a weighton one side of the pivot thereofconstantly tending to move the same on its pivot by gravity.

6. In a device of the character described a cap comprising a covermember and a flange extending therefrom, a fixed member on which saidcap is mounted to rotate, a cam fixed to the cap and enclosed thereby, aheat expansible metallic member and a connection between the same andsaid cam, whereby movement of the cap changes the position of the saidheat expansible member.

7. In combination with the devices specified in claim 6, a scale and anindex operable by the capto indicate the movement of the heat expansiblemember in terms of. temperatura 8. In an apparatus of the characterdescribed, a base, a responsive device to` one side of said base, anelectric switch mounted on the other side of said base, means operatedby said device to control said switch, a rotary cover ixed against axialmovement and housing said switch, and adjustable means between saidcover and controlling means whereby'the latter may be set when the coveris rotatably adjusted.

9. In an apparatus of the character de- .1923, at the city scribed, abase, a responsive device to one side of said base, an electric switchmounted on the other side of said base, means operated by said device tocontrol said switch, a

rotary cover fixed against axial movement and housing said switch, and aconnection between said cover and controlling means whereby the lattermay be set and the relation between it and the switch varied.

Witness vour hands this 21st day of April, of Milwaukee, in the countyof Milwaukee, State of Wisconsin.

WALTER c. LINDEMANN. EDWIN A. RUTENBER.

